When Windows 7 released, it included a 64-bit version of Internet Explorer. However, the 64-bit version was not very different from the 32-bit version, except that it wasn’t compatible with any plugins (at the time, Flash, Java, and everything else under the sun still only had 32-bit browser plugins).

Now in Windows 8, searching for IE only yields a single result:

What’s interesting about this is that IE now has 3 different browsers: the 32- and 64-bit desktop versions (like Windows 7), as well as the new immersive (formerly known as “Metro”) browser. On Windows 8, they’ve streamlined the experience to just give you the right browser.

So how do you run the 64-bit browser?

If you’re using the immersive IE, you get it automatically. If you’re using the desktop IE, you need to enable the Enhaned Protected Mode option. This is hidden deep in the jungle of IE’s advanced settings, under the Security section:

Protected Mode was introduced in IE 7, and was the first major effort to introduce sandboxed security (among other measures) in IE.

Enhanced Protected Mode takes this further, and leverages benefits only available to a 64-bit process. For example, ASLR is much more effective spread over a 64-bit address space than a 32-bit one.

With EPM enabled, we can verify that IE is now running in 64-bit mode by checking which executable is launched for a new tab. This can be done via the Task Manager. In the new Windows 8 task manager, the IE processes for each tab show up under Background Processes:

If you right-click any of these processes and view Properties, you can see the executable that’s running. It’s pretty easy to tell if it’s 32 or 64-bit:

Pros & Cons

Enabling EPM is a tradeoff, but the IE team has done a great job of making it fairly painless. The biggest drawback of EPM is that many plugins, like Java, are not yet compatible with the changes introduced in IE10 (Flash does work, but it’s about the only thing that does currently). Similar to the immersive IE experience, this leaves you basically without plugins. However, on any page which uses a plugin you’ll get a simple prompt to disable EPM for that site only:

Just click Disable if you want to allow that site to run the plugin needed. IE will reload the page in a new 32-bit process and the plugin will continue to work as always. Note: this does mean that you will need 32-bit versions of any plugins.

The biggest reason in favor of enabling EPM is simply that it makes your browsing experience more secure. And with the slight bit of overhead, why not?